KENNEDY SPACE CENTER, FLA. - On Launch Pad 17-B, Cape Canaveral Air Force Station, the Boeing Delta II rocket with the Mercury Surface, Space Environment, Geochemistry and Ranging (MESSENGER) spacecraft aboard waits for rollback of the mobile service tower and a second launch attempt in two days. The first attempt Aug. 2 was postponed due to lightning potential from residual clouds that were associated with Tropical Storm Alex. The launch of MESSENGER on a seven-year journey to the planet Mercury is rescheduled for this date at 2:15:56 a.m. EDT at the opening of a 12-second launch window. MESSENGER will fly by Earth, Venus and Mercury several times to burn off energy before making its final approach to the inner planet on March 18, 2011. MESSENGER was built for NASA by the Johns Hopkins University Applied Physics Laboratory in Laurel, Md.